FIR filters are commonly used in signal processing designs for signal conditioning. FIR filters receive an input signal and are generally configured to block pre-specified frequency components of the input signals. The resultant output signal from an FIR filter can be equal to the input signal with the pre-specified frequency components of the input signal removed or substantially attenuated. FIR filters are commonly employed in various signal processing applications such as communications and video/audio processing.
FIR filters are generally implemented either using analog components to filter continuous analog waveforms or digitally to filter digital (discrete) waveforms. Implementing an FIR filter in a circuit can present challenges with respect to power consumption and footprint (i.e., the amount of space taken up by the circuit). Multiple techniques have been proposed to implement digital FIR filters. The most common approach is the multiply and accumulate (MAC) approach. This approach can be derived directly from the mathematical formula representing the impulse response of the FIR filter expressed below in equation 1. However, a MAC approach to implementing an FIR filter can often require numerous switching stages, all of which in aggregate can consume a significant amount of power during the operation of the FIR filter. Furthermore, the circuitry required to implement the numerous switching stages in a conventional FIR filter can also occupy a large amount of space on a circuit board or device that includes the FIR filter.
Thus, an approach to implementing an FIR filter that requires less power and less space is desirable in order to decrease the operational costs associated with including an FIR filter in any given signal processing system.